The present invention relates to a liquid crystal display device and more particularly, to a liquid crystal display device of a narrower frame width that can ensure reliability of a seal part.
A liquid crystal display device includes: a TFT substrate where pixels each including a pixel electrode, a thin film transistor (TFT) and the like are arranged in a matrix; a counter substrate opposed to the TFT substrate; and liquid crystal sandwiched between the TFT substrate and the counter substrate. The liquid crystal display device forms an image by controlling transmittance of light through liquid crystal molecules on a per-pixel basis.
Being flat and light in weight, the liquid crystal display device has been finding wider applications in various fields. Compact liquid crystal display devices have been widely used in cellular phones, DSCs (Digital Still Cameras) and the like. Medium- and small-sized liquid crystal display devices are faced with a strong demand for enlarging a display region while maintaining a small outside configuration. Accordingly, the liquid crystal display device is reduced in width between an edge of the display region and an edge of the device. Namely, the device is adapted to a so-called narrow frame design. The device having the narrower frame is reduced in seal width of a sealing material bonding the TFT substrate and the counter substrate together and hence, is faced with a problem of a bonding force of the seal part.
An alignment film for initial alignment of the liquid crystal molecules is formed on each of the surfaces of the TFT substrate and the counter substrate, on which surfaces the TFT substrate and the counter substrate make contact with the liquid crystal. The prior-art technique has adopted a structure where the alignment film is not formed on the seal part in order to increase the reliability in the bonding force of the seal part. In the case of the narrow frame design, however, it is difficult to exclude the alignment film from the seal part. To address the reliability in the bond of the seal part, therefore, consideration must be given to the bond strength between the sealing material and the alignment film and the bond strength between the alignment film and an underlying film thereof.
As a technique for preventing the rubbing off of the alignment film on projections resulting from wiring on the display region, Japanese Unexamined Patent Application Publication No. 2012-189856 suggests an approach to increase the bond strength of the alignment film by applying ITO (Indium Tin Oxide) on the projections. Further, Japanese Unexamined Patent Application Publication No. Hei 10-206871 discloses a structure where the wiring is formed of ITO and the ITO wiring is laid under the seal part and extended to a terminal part. Japanese Unexamined Patent Application Publication No. Hei 10-206871 does not describe a range of applying the alignment film.